The plan is to continue investigation of determinants of cardiovascular disease (CVD) in a large, prospective cohort study of long duration, comprised of 121,700 US female registered nurses who have been followed since 1976 and are currently age 51-76 years. Continued follow-up will permit evaluation of a number of new and timely hypotheses regarding dietary and hormonal risk factors for coronary heart disease (CHD) as well as ischemic and hemorrhagic stroke. In addition, follow-up of two new and important endpoints, sudden cardiac death (SCD) and congestive heart failure (CHF), will be established, allowing them to examine the effect of atherogenic risk factors, physical activity and weight change on risk of SCD, as well as implement a methodology for confirming CHF. The Nurses' Health Study was begun in 1976 to study risk factors for breast cancer. In 1979, funding for risk factors of CVD was secured. Biennial mailed questionnaires gather detailed, updated information about a large number of exposures, including diet, smoking physical activity, postmenopausal hormone use, and psychosocial and behavioral factors. Incident reports of myocardial infarction and stroke are confirmed an classified by review of medical records, and similar procedures will be extended to confirm CHF and SCD. Fatal CVD events are documented by death certificates and confirmed by review of hospital medical records, autopsy reports and interviews with next of kin. Mortality follow-up exceeds 98 percent. The large size, prospective design, high follow-up rates, detailed and reliable long-term exposure and outcome information, and the availability of blood specimens on a large subgroup, combined with the relatively low cost, make this cohort a valuable and unique resource to study nutritional, hormonal and behavioral determinants of CVD in women. Continued funding of this grant will provide important new information about risk factors for CHD, stroke, SCD and CHF in this population of women who are now entering the age where CVD becomes the leading killer.